One of examples of interfaces for connection between electronic devices is universal serial bus (USB) 3.1 standard. The standard includes USB Type-C Cable and Connector Specification (hereinafter called Type-C standard). A host or a device supports an alternate mode (or alternative mode) such as repurposing the connector for docking-specific applications, under USB Type-C standard. In the alternate mode, several pins of USB Type-C connector can be reconfigured, and it is examined that display signals, for example, DisplayPort (registered trademark) signals are assigned to several pins of USB Type-C connector. A USB dock capable of simultaneously supporting DisplayPort standard and USB 3.0/3.1 (hereinafter called USB 3.x) standard is thereby implemented.
However, the maximum bit rate is 21.6 Gbps with signal lines of four lanes (four sets) under DisplayPort standard, but the USB dock cannot simultaneously receive USB 3.x signals and DisplayPort signals of four lanes, and can receive only DisplayPort signals of two lanes (lane 0 and lane 1) together with USB 3.x signal.